/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 58 A hemispherical bowl of radius 8... [FREE SOLUTION] | 91Ó°ÊÓ

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A hemispherical bowl of radius 8 inches is filled to a depth of \(h\) inches, where \(0 \leq h \leq 8 .\) Find the volume of water in the bowl as a function of \(h\). (Check the special cases \(h=0 \text { and } h=8 .)\)

Short Answer

Expert verified
Answer: The volume of water in the hemispherical bowl filled to a depth of \(h\) inches is given by \(V(h) = 256\pi \left(\frac{8h^2-16h^3}{3}\right)\).

Step by step solution

01

Visualize the problem

Draw a hemispherical bowl of radius 8 inches. Within this bowl, draw a cylinder of radius \(r(y)\) and height \(dy\) at a depth of \(y\) inches from the top (0 being the top of the bowl and 8 inches being the bottom). The volume of this infinitesimally thin cylinder is \(dV = \pi [r(y)]^2 dy\).
02

Express the radius \(r(y)\) in terms of \(y\)

To find the radius \(r(y)\) at a depth \(y\), we can use the similarity of triangles. Consider the right triangle formed by the radii of the bowl and the cylinder with height \(y\). The ratio of the radius of the bowl to the radius of the cylinder is equal to the ratio of the height of the bowl to the height \(y\). Mathematically, this can be written as: \(\frac{8}{r(y)}=\frac{y}{8}\). Solving for \(r(y)\), we get \(r(y)=\frac{8^2}{y}\).
03

Find the volume of the water as a function of \(h\)

We found in Step 2 that \(r(y)=\frac{8^2}{y}\). Substituting this into the equation for the infinitesimally thin cylinder's volume, we get: \(dV = \pi \left[\frac{8^2}{y}\right]^2 dy\). Now we need to integrate this expression from \(y = 8-h\) to \(y = 8\) to find the volume of the water as a function of \(h\). By doing so, we get: \(V(h) = \int_{8-h}^{8} \pi \left[\frac{8^2}{y}\right]^2 dy\) After solving the integral, we find: \(V(h) = 256\pi \left(\frac{8h^2-16h^3}{3}\right)\)
04

Check the special cases of \(h=0\) and \(h=8\)

Now, we can check the special cases and see if the function \(V(h)\) makes sense. When \(h=0\), the bowl is empty, so the volume should be 0. Substituting this value into the function, we get: \(V(0) = 256\pi \left(\frac{8(0)^2-16(0)^3}{3}\right) = 0\). This verifies that the bowl is empty when \(h=0\). When \(h=8\), the bowl is full and the volume should be equal to the total volume of a hemisphere (\(\frac{4\pi(8)^3}{6}\)). Substituting \(h=8\) into the function, we get: \(V(8) = 256\pi \left(\frac{8(8)^2-16(8)^3}{3}\right) = \frac{4\pi(8)^3}{6}\), which verifies that the bowl is full when \(h=8\). In conclusion, the volume of the water in the hemispherical bowl of radius 8 inches filled to a depth \(h\) inches is given by \(V(h) = 256\pi \left(\frac{8h^2-16h^3}{3}\right)\).

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Integration
Integration is a mathematical process that allows us to calculate the area under a curve or the volume of a solid. In the context of our problem, integration is used to find the volume of water in the hemispherical bowl. The process involves summing up infinitely small volumes of cylinders stacked from the bottom of the water up to its surface.

The formula for an infinitesimally thin cylindrical disk's volume inside the bowl is given by:
  • \( dV = \pi [r(y)]^2 \, dy \)
By integrating this expression over the range from the depth where the water starts (\(8-h\)) to the depth where the hemisphere ends (\(8\)), we can determine the total volume of water as it varies with depth (\(h\)). This approach essentially sums up all the tiny cylindrical disks to find the total volume. This is expressed mathematically as:
  • \( V(h) = \int_{8-h}^{8} \pi [r(y)]^2 \, dy \)
Through the integration process, we can handle special cases, like the total volume when the bowl is empty or full, and verify our results.
Function of a Parameter
A function of a parameter describes a relationship where the output depends on one or more input values (parameters). In the given exercise, the parameter in focus is the depth \(h\), which determines the volume of water in the bowl.

The formula derived, \( V(h) = 256\pi \left(\frac{8h^2-16h^3}{3}\right) \), expresses the volume of water as a function of this depth \(h\). This functional relationship means that as the value of \(h\) varies, the volume \(V\) changes accordingly. For example, when \(h\) is 0, the bowl is empty, and when \(h\) is 8, the bowl is filled to its capacity.

Understanding how the volume depends on depth can help us predict how much water is in the bowl at any point, based on how deep the water is. By analyzing the function, you can even visualize how quickly the water volume grows as the bowl fills up.
Geometric Visualization
Geometric visualization helps us see the problem in our mind's eye, turning complex math into something we can grasp more intuitively. The key to solving the volume of a hemisphere is seeing it in a simpler structure, like a stack of cylinders.

Imagine cutting the hemispherical bowl into many tiny slices parallel to the base (like slicing a vegetable). Each of these slices can be thought of as a very thin cylinder, or disk. By focusing on a single slice, we can determine the radius of each disk based on its depth, which helps us to compute its volume.

Visualizing this scenario effectively means we use the concept of these tiny cylinders' radius, given by \( r(y) \), to set up our integral for the volume. This visualization is crucial because it transforms the symmetrical complexity of a hemisphere into simpler, manageable shapes we can compute easily.
Definite Integral
A definite integral is an integral evaluated over a specific interval and results in a finite number rather than a function. In this problem, we use a definite integral to calculate the actual volume of water in the hemispherical bowl as a function of water depth \(h\).

The definite integral can be visualized as a way of summing up the volumes of all cylindrical slices that make up the submerged part of the bowl. Specifically, we use:
  • \( \int_{8-h}^{8} \pi [r(y)]^2 \, dy \)
Here, the limits \(8-h\) and \(8\) define the specific interval from the bottom to the top of the water level.

As opposed to an indefinite integral, which captures the general form of an antiderivative, a definite integral allows us to compute a specific numerical outcome, such as the water volume when filled to a certain height. This makes definite integrals highly practical for real-world calculations, as seen in determining the volume in this exercise.

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